Heretofore, in an automated assembly line for automobiles, for example, clamping by a clamping apparatus is carried out, in a state in which pre-formed body panels are overlapped and positioned, and an assembly step is carried out whereby the body panels are welded together.
Such a clamp apparatus, for example, as disclosed in U.S. Pat. No. 4,905,973, is equipped with a body, a drive unit which is made up from a cylinder connected to the body, and a clamp arm that projects externally with respect to the body. In addition, by displacing a piston of the drive unit by supplying air to the cylinder, a piston rod is displaced together with the piston, whereby the clamp arm, which is connected to a link mechanism constituted from a plurality of arms, is rotated through a predetermined angle. Consequently, a workpiece or the like can be clamped by the clamp arm.